V1 optimizer fix (#6350)
V1 optimizer fix (#6350)

* optimizer back to compat.v1

* add doc string to fix lint

tombstone/models,tombstone/models,derekjchow/models,alexgorban/models,derekjchow/models,alexgorban/models,tombstone/models,tombstone/models,derekjchow/models,derekjchow/models,alexgorban/models,alexgorban/models,alexgorban/models,tombstone/models,tombstone/models,derekjchow/models